Preheat your oven to 180°C (350°F).

Roll out your pastry dough on a lightly floured surface until it's about ¼ inch thick. Fit the rolled pastry into a tart pan and trim excess pastry.

In a large sauté pan over medium heat, add oil and sauté the leeks and sausage for about 5–7 minutes until softened.

In a mixing bowl, whisk together the eggs and cream until combined. Fold in the sautéed leeks and sausage.

Pour the mixture into the prepared pastry crust, spreading evenly.

Bake for 30–35 minutes. The tart is ready when the filling is set and golden brown.

Let it cool for about 10 minutes before slicing. Serve warm.